50 
IOWA ACADEMY OF SCIENCES. 
coming up to the electrode. A divalent element carries 
twice as much as a univalent; a trivalent three times as 
much. Electrolysis tells us, accordingly, that the magni- 
tude of electrical charges on ionized atoms in solution is 
always an integral multiple of that on the hydrogen atom. 
As Helmholtz says, “if we accept the hypothesis that 
elementary substances are composed of atoms, we can not 
avoid the conclusion that electricity, positive as well as 
negative, is divided into definite elementary particles which 
behave like atoms of electricity.” 
The fact of the ultimate divisibility of an electric charge 
is more clearly grasped from the behavior of an ionized 
gas. When a gas is subjected to the influence of Roentgen 
rays it takes on conductivity. This conductivity is due to 
the presence of minute particles of electricity mixed with 
the gas. These particles can be filtered out of the gas 
through a plug of cotton wool. They can also be attracted 
or repelled out by the action of a strong electric field. The 
mass of these particles of electricity was determined by 
J. J. Thomson and other experimenters in various ways. 
It would take too long to discuss any of these methods in 
detail. The principal method, however, consisted in mak- 
ing the particles nuclei of visible vapor particles. In this 
manner, a cloud was formed and from the rapidity of 
motion of the descending cloud, under the action of 
gravity, the number of particles in a given charge was 
quite accurately determined. Knowing the number, the 
mass of a particle of electricity was easily obtained. The 
magnitude of this mass was found to be about toVo of the 
mass of a hydrogen atom. No matter what the nature of 
the ionized gas, it was always found that the mass of the 
particle was unvaried and that the charge it carried was 
negative in sign. 
These negatively electrified particles denoted by J. J. 
Thomson as corpuscles are accepted by him as the 
primordial units of all matter. We recognize also that 
these corpuscles consist of ether under a very intense 
stress. The ether in the corpuscle is so much concentrated 
